Liquid crystal display (LCD) technology has been developed aggressively over recent decades and has obtained significant progress in both screen size and display quality. Currently, one drop filling (ODF) process is one of the common processes in manufacturing a liquid crystal display panel for filling liquid crystal and can save the time for filling liquid crystal in the panel and improve yield. One of the bottlenecks of the conventional ODF process is insufficient margin for the amount of the filled liquid crystal in operation. When the amount of the filled liquid crystal in the ODF process is not accurate, or when heights of the spacers between a color filter substrate and a thin film transistor (TFT) array substrate are not uniform, void bubbles or gravity defects tend to occur in the liquid crystal layer. Void bubbles refer to the bubbles generated inside a LCD panel during a low temperature test due to shrinkage of the liquid crystal. At a low temperature, both the spacers and the liquid crystal are subjected to certain shrinkage. When the amount of shrinkage of the spacers is smaller than that of the liquid crystal, bubbles may be generated in the liquid crystal panel. Gravity defect refers to an excessive cell gap in the panel due to settlement of the liquid crystal at the bottom of the panel under the gravity when the panel is in an upright state. When the liquid crystal is expanded at a high temperature, gravity defects deteriorate.
Typically, for the spacers disposed between the color filter substrate and the TFT array substrate in a liquid crystal panel, on one hand, the smaller the distribution density of the spacers is, that is, the smaller the number of the spacers per unit area is, the more unlikely the void bubbles occur in low temperature; however, in that case, the pressure resistance of the panel is reduced and it tends to suffer from gravity defect. On the other hand, the larger the distribution density of the spacers is, the more likely the void bubbles occur; however, the pressure resistance of the panel is enhanced and it is unlikely for gravity defect to occur. Typically, the larger elasticity of the spacers is, and the larger the margin of the amount of the filled liquid crystal in the ODF process is, so that the possibility of void bubbles and gravity defects is low, but pressure resistance of the LCD panel tends to decrease. Therefore, it is critical to select an appropriate material as well as a desired distribution density for the spacers between the color filter substrate and the thin film transistor substrate in order to improve the margin of amount of the filled liquid crystal in the ODF process and the pressure resistance.
In a conventional large size LCD panel, it is typical to use column spacers made of a photoresist resin attached to the color filter substrate so as to maintain the cell gap of the LCD panel. Thus, it is necessary for the column spacers to comprise an appropriate material and a desired distribution density so as to increase margin of the amount of the filled liquid crystal in the ODF process and enhance pressure resistance of the LCD panel. It is more preferable that the margin of the amount of the filled liquid crystal in the ODF process can be improved while the pressure resistance of the LCD panel can be maintained.